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idotnetdev/GoogleMapsAPIProjection.cs

Forked from evilz/GoogleMapsAPIProjection.cs
Created July 23, 2017 07:17
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  1. @evilz evilz created this gist Aug 19, 2015.
    33 changes: 33 additions & 0 deletions GoogleMapsAPIProjection.cs
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    Original file line number Diff line number Diff line change
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    public class GoogleMapsAPIProjection
    {
    private readonly double PixelTileSize = 256d;
    private readonly double DegreesToRadiansRatio = 180d / Math.PI;
    private readonly double RadiansToDegreesRatio = Math.PI / 180d;
    private readonly PointF PixelGlobeCenter;
    private readonly double XPixelsToDegreesRatio;
    private readonly double YPixelsToRadiansRatio;

    public GoogleMapsAPIProjection(double zoomLevel)
    {
    var pixelGlobeSize = this.PixelTileSize * Math.Pow(2d, zoomLevel);
    this.XPixelsToDegreesRatio = pixelGlobeSize / 360d;
    this.YPixelsToRadiansRatio = pixelGlobeSize / (2d * Math.PI);
    var halfPixelGlobeSize = Convert.ToSingle(pixelGlobeSize / 2d);
    this.PixelGlobeCenter = new PointF(halfPixelGlobeSize, halfPixelGlobeSize);
    }

    public PointF FromCoordinatesToPixel(PointF coordinates)
    {
    var x = Math.Round(this.PixelGlobeCenter.X + (coordinates.X * this.XPixelsToDegreesRatio));
    var f = Math.Min(Math.Max(Math.Sin(coordinates.Y * RadiansToDegreesRatio), -0.9999d), 0.9999d);
    var y = Math.Round(this.PixelGlobeCenter.Y + .5d * Math.Log((1d + f) / (1d - f)) * -this.YPixelsToRadiansRatio);
    return new PointF(Convert.ToSingle(x), Convert.ToSingle(y));
    }

    public PointF FromPixelToCoordinates(PointF pixel)
    {
    var longitude = (pixel.X - this.PixelGlobeCenter.X) / this.XPixelsToDegreesRatio;
    var latitude = (2 * Math.Atan(Math.Exp((pixel.Y - this.PixelGlobeCenter.Y) / -this.YPixelsToRadiansRatio)) - Math.PI / 2) * DegreesToRadiansRatio;
    return new PointF(Convert.ToSingle(latitude), Convert.ToSingle(longitude));
    }